Just to add, interestingly, Singer also purchased General Precision from Librascope.
Librascope/General Precision were the folks that had earlier acquired Royal-McBee. Royal-McBee developed the wonderful (some consider the first "personal" computer) LGP-30 vacuum-tube, magnetic drum computer that was designed by Manhattan Project theoretical physicist Stanley Frankel.
Frankel had quite a legacy in the world of computing, having contributed to the design of the delay-line-based Packard Bell PB-250(with Max Palevsky), and development of a custom high-speed computer for Continental Oil Company called CONAC (used for data reduction of sounding operations search for oil deposits).
Frankel also developed an early electronic calculator design that was purchased by Smith Corona/Marchant (SCM) and produced as the CRT-display SCM Cogito 240 calculator, augmented with Square Root as to Cogito 240SR.
Frankel also collaborated with SCM on the development of the logic for the first set of LSI integrated circuits that were used in the later Nixie-tube display Cogito calculators.
He also developed a very interesting calculator, based somewhat on the principles of the LGP-30 computer for Diehl in West Germany. The machine was fully transistorized and used only 142 transistors in its logic. It was based on magnetostrictive delay lines (two of them), and was a fully microcoded architecture, I believe the first electronic calculator to be completely microcoded.
Since read-only memory (for the microcode) was either physically very large, or complex and expensive to build at the time (diode ROM, wire rope ROM), the microcode was loaded into the calculator at power-up time from a two channel punched metal tape. One channel provided the clocking, and the other channel provided the bits.
It took just under a minute from when the calculator was powered on until the microcode was loaded into a delay line, and from there, all operations of the machine were controlled by the microcode in the delay line.
The machine was able to be implemented with so few transistors because the microcode word was quite wide, and was designed so that it was sequentially interpreted as the bits streamed out of the delay line, so not all that many flip flops were needed. Working registers were stored in the other delay line, along with program steps (yes, the machine was programmable).
The design was very elegant. The machine debuted as the Diehl Combitron, and the cool thing about its design was that it was really easy to augment by just changing the microcode tape (which was quite easily done...bugfixes could be easly installed even by end-users, though such was discouraged).
Soon after the Combitron was introduced, an augmented version was introduced called the Combitron-S that added a small amount of I/O circuitry and additional microcode to implement operations to allow the addition of an external punched paper tape reader/punch.
An interesting aspect of electronic calculator history is that there are a number of people whose names pop up at various points in time during the evolution of the technology. Frankel was one of those, along with a cast of a few others, all of whom had major impacts in the realm of electronic calculator (and the eventual evolution of the electronic calculator into what became the microcontroller/microprocessor that spurred the development of the personal computer).
Jon,
I have an Emulex QD21 that I could part with. I was hoping to attend VCF MW but it looks very doubtful at this point. I also have a spare DEQNA or DELQA. I have not tested these boards to verify that they work although I could test the ethernet boards on a PDP-11. Hans-Ulrich Hölscher mentioned work he did testing MicroVAX II transfers with Lee Gleason’s MicroVAX I project to transfer disk images on bare metal (no-OS) MicroVAX systems. I think that would be your best bet to recover your ESDI disk. If you don’t have any luck at the VCCF MW getting what you need, send me an email and we can work something out.
Best,
Mark
FYI, SDF retro computing and home brew exhibition is scheduled for September 30 to October 1 in Seattle WA . Link to the exhibit is at https://sdf.org/icf/ and https://icm.museum/
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Tarek Hoteit
tarek(a)infocom.ai
+1 360-838-3675
https://infocom.ai
